In a known machine of this type (German published patent application DE-OS 42 41 320), the working part is driven via the shaft, and in the manner like a machine with spur toothing, the working parts between the work faces are reduced or increased in size for pumping the medium. Conversely, such a machine can also act as a motor, in that medium is pumped under pressure into the work chambers and by increasing the size of the work chambers generates a drive of the shaft. In both cases, two working parts in the machine housing are moved to rotate, which makes correspondingly high demands of the rotary bearing and the axial bearing and has a major power limitation with reference to the working pressure.
In another known machine of this type (U.S. Pat. No. 3,236,186), the two parts meshing with their teeth with one another on their face ends are disposed in a housing with a spherical interior, and in the center, a spherical embodiment on the parts makes the tumbling motion of the parts relative to one another that occurs upon rotation possible. Once again, there is a correspondingly major demand made of the rotary bearing of the parts as well as their axial bearing, so that above all narrow limits are set with regard to the magnitude of the working pressure. Moreover, the effort and expense for production of such convex or concave flank faces on the teeth of the spur toothing is extraordinarily high.
In these known pumps or motors, for engineering reasons conduits forming the inlet and outlet to and from the work chambers branch off radially to the working parts, so that once again there is a radial load on the working parts that corresponds to the power pressure. Aside from this, the flow of the medium via the radial peripheries of the edges controlling the orifices of the conduits causes corresponding wear to the working parts, which with a corresponding increase in the power loss over the service life of the machine likewise increases. Because of this wear, increasing on the spherical surface of the teeth, a leak from one work chamber to the next occurs in this outer spherical region of the teeth, and the otherwise advantageous slight overlap of the radial face end of the teeth with the diametrically opposed spherical wall has an especially adverse effect.